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UNIVERSITY  OF  ILLINOIS 

Agricultural  Experiment  Station 


BULLETIN  No.  250 


THE  VALUE  OF  MINERAL  SUPPLEMENTS 
IN  SWINE  FEEDING 


BY  JOHN  B.  EICE 

WITH   AN   INTRODUCTION    BY 

H.  H.  MITCHELL 


URBANA,  ILLINOIS,  MAY,  1924 


CONTENTS  OF  BULLETIN  No.  250 

•  PAGE 

INTRODUCTION 89 

The  Mineral  Requirements  of  Animals 89 

The  Mineral  Problem  in  Swine  Feeding 91 

Improving  the  Calcium  Retention  of  Swine  on  Grain  Rations 91 

Improving  the  Quality  of  Bone  on  Grain  Rations. . 92 

The  Value  of  Different  Minerals  as  Supplements  to  Grain  Rations 93 

Mineral  Mixtures — Homemade  and  Commercial 95 

The  Economic  Value  of  Mineral  Feeding 96 

FEEDING  EXPERIMENTS 97 

EXPERIMENT  I:  MINERAL  SUPPLEMENTS  USED  WITH  CORN, 
MIDDLINGS,  AND  TANKAGE,  WITH  AND  WITHOUT  RAPE 

PASTURE 98 

EXPERIMENT    II:     PROVIDING    A    MINERAL    MIXTURE    IN    THE 

SELF-FEEDER  TO  PIGS  ON  PASTURE 100 

EXPERIMENT  III:  MINERAL  SUPPLEMENTS  USED  WITH  CORN, 
LINSEED  OIL  MEAL,  AND  MIDDLINGS,  WITH  ACCESS  TO  BLUE- 
GRASS  PASTURE 102 

MINERAL  SUPPLEMENTS  FOR  PREGNANT  AND  LACTATING  SOWS  106 

CONCLUSIONS  .                                                                                                        .  110 


THE  VALUE  OF  MINERAL  SUPPLEMENTS 
IN  SWINE  FEEDING 

BY  JOHN  B.  EICE,1  ASSISTANT  CHIEF  IN  SWINE  HUSBANDRY 

WITH   AN   INTRODUCTION    BY 

H.  H.  MITCHELL,  ASSOCIATE  CHIEF  IN  ANIMAL  NUTRITION 

INTRODUCTION 

THE  MINERAL  REQUIREMENTS  OF  ANIMALS 

Animals  require  for  their  proper  growth  and  development  twelve 
or  fifteen,  or  possibly  more,  mineral  elements,  retaining  daily  during 
active  growth  two  to  three  ounces  for  every  thousand  pounds  of  live 
weight.  Fortunately  it  is  not  necessary  in  the  practical  rationing  of 
farm  animals  to  consider  more  than  two  or  three  of  these  elements. 
The  largest  requirement  of  mineral  matter  by  growing,  breeding,  and 
lactating  animals  is  for  bone  growth,  or  for  the  secretion  of  a  food 
(milk)  capable  of  supporting  vigorous  bone  growth  in  their  young. 

About  85  percent  of  the  ash  of  bones  is  calcium  phosphate.  Hence, 
quantitatively,  the  most  urgent  need  for  mineral  matter  by  farm 
animals  is  for  calcium  and  phosphorus.  It  has  been  estimated  that 
over  80  percent  of  the  mineral  matter  retained  in  the  bodies  of  grow- 
ing animals  is  calcium  and  phosphorus.  It  is  natural,  therefore,  that 
the  calcium  and  phosphorus  requirements  of  animals  and  the  calcium 
and  phosphorus  content  of  farm  feeds  should  have  received  the  most 
attention  in  experiments  concerned  with  the  mineral  requirements 
of  farm  animals.  Such  experiments  have  yielded  no  definite  evi- 
dence that  farm  rations  are  ever  likely  to  be  deficient  in  the 
many  other  mineral  elements  needed  by  growing  animals,  with  the 
exception  of  iodin.  This  element,  occurring  in  mere  traces  in  most 
feeds,  may  at  times,  and  particularly  in  certain  restricted  localities, 
be  present  in  deficient  amounts  in  otherwise  well-balanced  rations. 
This  deficiency  has  been  definitely  demonstrated  with  breeding 
animals,  and  occasionally  with  young  growing  animals,  especially 
calves.  In  the  case  of  breeding  animals  it  has  been  indicated  by 
the  birth  of  dead  offspring  marked  with  those  deformities,  such 
as  hairlessness  and  goiter,  resulting  from  the  abnormal  develop- 
ment and  functioning  of  the  thyroid  gland.  The  administration  of 
small  amounts  of  potassium  iodid  or  sodium  iodid  to  breeding  animals 


1  In  Experiment  III,  reported  on  pages  103  to  110,  the  bone  measurements  and 
analyses  were  made  by  the  Division  of  Animal  Nutrition,  and  the  responsibility 
for  the  discussion  of  these  data  is  assumed  by  H.  H.  Mitchell. 


90  BULLETIN  No.  250  [May, 

in  those  localities  where  goiter  is  prevalent,  seems  to  be  an  effective 
remedy  against  this  condition,  but  offers  no  excuse  for  the  general 
administration  of  iodids  to  farm  stock. 

The  evidence  of  a  possible  deficiency  of  farm  rations  in  other 
mineral  elements,  such  as  iron,  needed  by  animals  in  very  small 
amounts  and  present  in  mere  traces  in  farm  feeds,  is  admittedly 
negative.  However,  until  a  definite  suspicion  of  such  defiencies  is 
justified  by  experimental  evidence,  a  general  consideration  of  the 
mineral  requirements  of  farm  animals  may  reasonably  be  restricted 
to  calcium  and  phosphorus. 

It  may  be  stated  as  a  general  proposition  that  the  leguminous 
roughages  are  adequate  sources  of  calcium  and  phosphorus  except 
possibly  under  conditions  of  excessive  demands  for  bone-forming 
materials,  as  with  high-producing  dairy  cows.  The  non-leguminous 
roughages  are  much  inferior  in  this  respect,  particularly  as  regards 
their  content  of  calcium.  Pasture  grasses  are  known  to  vary  in  their 
mineral  content  according  to  the  composition  of  the  soil  upon  which 
they  are  grown.  In  fertile  regions,  however,  they  can  be  considered 
reliable  tho  not  particularly  rich  sources  of  mineral  nutrients. 

From  these  general  observations,  it  may  be  concluded  that  animals 
raised  largely  upon  liberal  amounts  of  a  good  roughage  are  not  in 
danger  of  mineral  under-nutrition.  Sheep  and  beef  cattle  come  within 
this  category.  Dairy  heifers  and  dairy  cows  offer  peculiar  problems 
of  their  own.  The  dairy  heifer,  by  being  generally  removed  from  its 
dam  at  an  early  age  and  fed  artificial  rations  composed  largely  of 
feeds  low  in  bone-forming  nutrients,  may  often  receive  insufficient 
mineral  nourishment.  The  dairy  cow,  because  of  the  extensive  drain 
on  its  mineral  stores  occasioned  by  the  secretion  of  amounts  of  milk 
enlarged  to  unnatural  proportions  by  long  and  careful  breeding, 
should,  in  the  most  successful  dairy  practice,  be  fed  rations  carefully 
balanced  with  respect  to  calcium  and  phosphorus.  The  horse,  also, 
should  be  raised  with  special  regard  to  its  mineral  supply,  since  its 
commercial  value  depends  so  much  upon  optimum  bone  strength  and 
development. 

In  contrast  with  the  roughages,  the  seeds  and  their  by-products 
cannot  be  considered  good  bone  foods.  While  some  of  these  feeds, 
particularly  cottonseed  meal  and  wheat  bran,  are  among  the  richest 
sources  of  phosphorus  available  on  the  farm,  their  content  of  calcium 
is  uniformly  low,  and  rations  composed  largely  of  seeds  and  their 
by-products  may  be  considered  generally  deficient  in  calcium,  except 
for  the  maintenance  and  fattening  of  mature  stock.  Hence,  in  the 
feeding  of  growing  pigs,  brood  sows,  and  growing  and  laying  poultry, 
there  is  urgent  call  for  a  proper  supplementing  of  the  ration  in  order 
to  correct  its  calcium  deficiencies. 


1924]  MINERAL  SUPPLEMENTS  IN  SWINE  FEEDING  91 

THE  MINERAL  PROBLEM  IN  SWINE  FEEDING 

For  physiological  and  economic  reasons  the  major  part  of  the 
ration  of  swine  will  always  be  grain,  and  the  nutritive  deficiencies  of 
grains  as  feeds  are  therefore  of  first  importance  to  swine  feeders.  The 
advantages  of  increasing  the  protein  of  cereal  rations  by  the  addi- 
tion of  supplements  rich  in  this  nutrient,  such  as  skim  milk,  tankage, 
linseed  oil  meal,  soybeans,  and  soybean  oil  meal,  seem  now  well  estab- 
lished, and  such  supplements  constitute  an  essential  part  of  the  most 
successful  rations  for  swine.  The  advantages  of  vitamin  supplements 
to  cereal  feeds  are  just  beginning  to  be  investigated,  and  while  it  seems 
that  with  some  cereal  feeds  such  supplementing  is  required,  no  gen- 
eral recommendations  are  warranted  at  present.  The  need  of  mineral 
supplements  to  cereal  feeds  has  been  realized  for  many  years,  but 
whether  this  correction  should  be  made  by  the  use  of  feeds  rich  in 
minerals,  or  by  the  use  of  minerals  as  such,  is  still  an  open  question. 
If  minerals  as  such  are  to  be  recommended,  what  advantages  may  be 
expected  from  their  use,  and  what  minerals  are  the  most  valuable  as 
supplements  to  cereal  grains  and  by-products,  are  questions  upon 
which  the  experimental  evidence  is  conflicting. 

Quantitatively  the  greatest  need  of  minerals  by  the  growing  ani- 
mal, the  pregnant  animal,  and  the  lactating  animal  is  for  calcium  and 
phosphorus,  the  main  constituents  of  bones.  The  greatest  mineral 
deficiency  of  cereals  is  in  calcium.  Since  rations  for  swine  consist  so 
largely  of  the  cereal  grains  and  their  by-products,  the  question  of 
mineral  supplements  in  swine  feeding  involves  mainly  calcium  and 
the  use  of  feeds  and  minerals  that  are  richest  in  this  element  in 
forms  suitable  for  animal  use.  It  seems  possible  also  that  the  phos- 
phorus content  of  cereals  is  not  sufficiently  high,  when  considered  in 
relation  to  the  amounts  consumed  by  pigs,  to  provide  fully  for  the 
requirement  of  maximum  bone  growth,  tho  the  evidence  on  this  point 
is  not  sufficient  to  warrant  a  definite  conclusion.  The  need  of  common 
salt,  also,  by  swine  as  a  supplement  to  their  cereal  feed  is  fully 
recognized. 

IMPROVING  THE  CALCIUM  KETENTION  OF  SWINE  ON  GRAIN  KATIONS 

It  has  been  clearly  shown  by  careful  balance  experiments  that 
cereal  feeds  alone,  and  in  particular  corn,  do  not  provide  enough 
calcium  to  permit  of  any  considerable  retention  of  this  element  for 
bone  and  tissue  growth.  In  fact,  Forbes  contends  that  corn  alone,  or 
corn  supplemented  by  the  seed  by-products,  linseed  oil  meal  and 
wheat  middlings,  cannot  maintain  the  growing  pig  in  calcium 
equilibrium.  While  his  mineral  balance  data  support  this  conclusion, 
the  slaughter  records  and  carcass  analyses,  where  such  were  made, 
in  most  cases  indicate  either  no  loss  of  calcium  and  no  impoverishment 


92 


BULLETIN  No.  250 


[May, 


of  the  skeleton  in  this  element,  or  a  considerable  growth  of  skeleton  and 
a  corresponding  retention  of  calcium.1  Such  records  appear  to  be  of 
more  significance  than  the  results  of  short  balance  periods.  A  per- 
sistent negative  calcium  balance  cannot,  therefore,  be  considered  char- 
acteristic of  animals  subsisting  upon  even  such  poor  mineral  feeds  as 
corn  and  the  feeds  with  which  it  is  commonly  fed.  In  other  words, 
on  a  low  calcium  intake  the  animal  body  possesses  the  power  to 
conserve  its  calcium  stores  against  any  serious  depletion,  by  a  more 
economical  use  of  the  calcium  in  its  feed. 

However,  it  is  equally  clear  that  mineral  additions  to  such  rations, 
either  in  feeds  rich  in  calcium  compounds,  such  as  skim  milk  and 
tankage,  or  in  mineral  supplements,  may  greatly  increase  the  reten- 
tion of  calcium  and  phosphorus  and  permit  the  normal  growth  of 
bone.  From  slaughter  tests  performed  by  Forbes  and  his  associates 
on  pigs  subsisting  for  twelve  weeks  on  rations  of  corn  alone,  and  on 
corn  plus  a  single  supplementary  feed  (Ohio  Bulletin  285),  it  may 
be  computed  that  the  average  daily  gain  or  loss  of  calcium  and  phos- 
phorus in  the  skeleton  alone  was  as  follows  for  the  different  lots: 

TABLE  1. — AVERAGE  DAILY  GAINS  OF  CALCIUM  AND  PHOSPHORUS  IN  THE  SKELETONS 

OF  PIGS  ON  RATIONS  OF  CORN  AND  A  SUPPLEMENTARY  FEED 
From  Slaughter  Records  Reported  by  Forbes  in  Ohio  Bulletin  285 


Ration 

Slaughter 
weight  of 
pigs 

Average  daily 
gain  of 
calcium 

Average  daily 
gain  of 
phosphorus 

Corn  alone  

Ibs. 
183 

gms. 
+0.069 

gms. 
+0.044 

Corn  and  soybeans  

172 

-0.229 

—0.086 

Corn  and  oil  meal  

199 

+0.220 

-+  0.136 

Corn  and  middlings  

201 

+0.081 

+0.118 

Corn  and  tankage  

190 

-f  1.202 

+0.583 

Corn  and  skim  milk  

216 

+1.882 

+0.900 

The  marked  effect  of  tankage  and  skim  milk  in  increasing  the 
retention  of  the  bone-forming  elements,  calcium  and  phosphorus,  is 
clearly  evident  from  these  figures.  In  short  balance  periods,  in  which 
the  intake  and  outgo  of  calcium  have  been  determined,  daily  reten- 
tions of  3  to  4.5  grams  of  calcium  have  been  obtained  at  the  Ohio 
Station  on  seed  rations  supplemented  with  minerals. 

IMPROVING  THE  QUALITY  OF  BONE  OF  SWINE  ON  GRAIN  RATIONS 

In  experiments  at  the  Nebraska  Station  (Bulletin  107),  as  well  as 
at  the  Ohio  Station  (Bulletins  283  and  347),  it  has  been  shown  that 
mineral  supplements  and  feeds  rich  in  minerals  do  not  have  an 


1  Ohio  Agricultural  Experiment  Station  Bulletin  213,  page  288 ;    and  Bulletin 
283,  pages  135,  347,  and  67-68. 


19SS4] 


MINERAL  SUPPLEMENTS  IN  SWINE  FEEDING 


93 


appreciable  effect,  if  any  at  all,  on  the  dimensions  or  the  volume  of 
the  bones,  but  that  they  may  markedly  increase  the  density,  the  thick- 
ness of  wall,  the  hardness,  and  the  breaking  strength.  As  Forbes  has 
well  said,  big  bone  can  be  obtained  by  breeding  for  it,  but  dense 
bone  only  by  feeding  for  it.  The  following  figures  taken  from  the 
Nebraska  report  show  clearly  the  favorable  effect  of  certain  rations 
on  the  breaking  strength  of  bones. 

TABLE  2. — COMPARATIVE  BREAKING  STRENGTH  OF  BONES  OF  HOGS 

ON  VARIOUS  EATIONS 
Average  Breaking  Strength  per  100  Pounds  Live  Weight 


Ration 

Femur 

Tibia 

Humerus 

Ulna-radius 

All  bones 

Corn  alone  

276 

252 

434 

341 

325 

Corn  75,  shorts  25  

343 

309 

555 

37ti 

396 

Corn  25,  skim  milk  75  ... 
Corn  90,  tankage  10  .... 
Corn  90,  ground  bone  10 

462 
559 
646 

360 
409 
465 

685 
740 
898 

529 
611 
715 

509 
580 
681 

An  increase  in  strength  of  more  than  100  percent  was  secured  by 
the  feeding  of  ground  bone  with  corn,  and  only  a  slightly  smaller 
increase  by  the  feeding  of  tankage.  These  increases  are  much  larger 
than  those  reported  by  Forbes,  who,  however,  started  his  experiments 
with  heavier  pigs,  weighing  100  pounds  or  more.  There  seems  to  be 
no  definite  upper  limit  to  the  storage  of  minerals  in  the  skeleton  and 
to  the  increased  density  and  strength  associated  with  it. 

THE  VALUE  OF  DIFFERENT  MINERALS  AS  SUPPLEMENTS 
TO  GRAIN  RATIONS 

Altho  there  is  every  reason  to  believe  that  the  rations  of  growing 
pigs,  and  of  breeding  stock  as  well,  may  be  balanced  properly  with 
respect  to  minerals  by  the  use  of  sufficient  amounts  of  mineral-rich 
feeds  and  pastures,  when  such  feeds  are  not  available  or  are  not  in 
common  use  the  possibility  of  using  mineral  supplements  to  advantage 
may  then  be  considered.  Several  experiment  stations  have  investigated 
the  value  of  various  mineral  mixtures  in  increasing  the  daily  gains 
of  growing  pigs  and  in  decreasing  the  cost  of  gains.  There  are,  how- 
ever, very  few  experiments  on  record  comparing  individual  mineral 
substances.  Experiments  of  this  character  have  been  reported  re- 
cently by  Forbes  and  his  associates  at  the  Ohio  Station  in  Bulletin 
347.  The  experiments  therein  reported  are  very  complete  and  con- 
stitute a  notable  contribution  to  the  literature  on  the  subject. 

The  basal  ration  in  those  experiments  consisted  of  corn  meal  7 
parts,  wheat  middlings  1  part,  and  linseed  oil  meal  1  part.  The 
mineral  supplements  tested  included  rock  phosphate  floats,  ground 
limestone,  a  precipitated  calcium  carbonate,  precipitated  bone  flour,  a 


94  BULLETIN  No.  250  [May, 

special  steamed  bone  flour,  and  in  one  experiment,  the  less  common 
supplements,  whiting  and  marl.  When  these  supplements  (except 
the  last  two)  were  added  to  the  basal  ration  in  amounts  providing  the 
same  daily  quantity  of  calcium  (5  grams),  the  bone  and  carbonate 
preparations  were  about  equally  efficient  in  causing  increased  reten- 
tion of  calcium  above  that  secured  on  the  basal  ration  alone.  The 
rock  phosphate,  however,  was  distinctly  inferior  in  this  respect.  Re- 
tention of  calcium  and  phosphorus  was  50  to  60  percent  greater  with 
the  other  supplements  than  with  rock  phosphate.  It  was  shown  by 
examination  of  certain  leg  bones  that  with  the  same  intake  of  supple- 
ments, the  volume  of  the  bone  was  not  greatly  affected  by  the  method 
of  feeding.  In  hardness,  density,  and  breaking  strength,  however, 
distinct  differences  appeared  among  the  groups.  No  distinction  was 
noted  between  the  bones  of  pigs  receiving  no  minerals  and  those 
of  pigs  receiving  rock  phosphate.  In  spite  of  a  greater  retention 
of  calcium  occasioned  by  the  rock  phosphate  supplement,  the  strength 
of  the  bones  was  not  improved  over  the  bones  of  the  no-mineral  pigs. 
The  supplements  having  the  most  marked  effect  on  the  physical  prop- 
erties of  the  bones  were  the  precipitated  calcium  carbonate  and  the 
steamed  bone.  These  supplements  in  eighty-six  days  caused  an  aver- 
age increase  in  the  breaking  strength  of  the  bones  of  25  to  45  percent 
over  the  no-mineral  ration.  The  initial  weight  of  these  pigs  was  137 
pounds;  with  younger  pigs  probably  much  greater  increases  would 
have  been  obtained. 

When  the  supplements  were  self -fed  (mixed  with  3  percent  of 
common  salt),  one  to  each  group  of  pigs,  the  steamed  bone  proved 
much  more  palatable  than  the  other  bone  preparations  and  than 
ground  limestone — which  in  turn  were  distinctly  more  palatable  than 
the  rock  phosphate  and  the  precipitated  calcium  carbonate.  Again 
the  rock  phosphate  produced  no  greater  strength  of  bone  in  relation 
to  live  weight  than  did  the  basal  ration  without  mineral  supplement, 
while  all  other  supplements  caused  marked  and  nearly  equal  increases 
in  bone  strength.  It  is  to  be  noted  that  the  large  excess  of  steamed 
bone  consumed,  as  compared  with  the  intake  of  the  other  supplements, 
apparently  produced  no  distinctly  greater  effect  than  a  quantity  half 
as  large  produced  in  the  other  experiments,  except  possibly  as  regards 
bone  hardness. 

In  the  two  experiments  reported  in  this  bulletin  in  which  the  di- 
gestibility of  the  rations  was  determined,  it  was  found  that  the  added 
mineral  supplements  had  no  effect  on  the  digestibility  of  protein,  car- 
bohydrate, or  fat.  It  is  also  worthy  of  note  that  the  carbonate  minerals 
could  not  be  clearly  distinguished  from  the  phosphate  minerals  in  these 
experiments  in  their  effect  on  calcium  or  phosphorus  retention  or  on 
the  strength  and  density  of  bone.  In  other  words,  there  is  no  reason 
to  doubt  that  the  basal  ration  used  contained  sufficient  phosphorus 


1924}  MINERAL  SUPPLEMENTS  IN  SWINE  FEEDING  95 

for  maximum  bone  growth  and  development.  The  advantage,  if  any, 
of  calcium  phosphate  supplements  over  calcium  carbonate  supplements 
is  in  their  greater  palatability  and  the  greater  tolerance  of  the  digestive 
system  for  phosphates  than  for  carbonates. 

Substantially  the  same  conclusion  is  justified  from  the  balance  ex- 
periments reported  by  Hart,  Steenbock,  and  Fuller  in  Eesearch  Bulle- 
tin 30  of  the  Wisconsin  Agricultural  Experiment  Station.  The  Wis- 
consin investigators  have  had  better  success  with  rock  phosphate  as  a 
mineral  supplement  to  a  seed  ration  than  has  Forbes,  tho  their  data 
are  not  as  numerous  as  those  of  Forbes,  and  in  some  respects  their 
results  are  inexplicable.  The  predominant  need  for  phosphorus  rather 
than  for  calcium  by  swine  on  cereal  rations,  indicated  by  earlier  ex- 
periments at  the  Wisconsin  Station  (Research  Bulletin  1),  has  not 
been  confirmed  at  other  stations  and  is  in  direct  contradiction  to  the 
more  extensive  work  of  Forbes. 

MINERAL  MIXTURES — HOMEMADE  AND  COMMERCIAL 

Mineral  supplements  are  cheap  and  concentrated  sources  of  cal- 
cium and  phosphorus,  and  if  wisely  chosen,  may  correct  satisfactorily 
the  mineral  deficiencies  of  grain  rations.  For  this  purpose,  both  phos- 
phate and  carbonate  preparations  of  calcium  may  be  used.  Bone 
meal,  particularly  steamed  bone  meal,  and  finely  ground  high-grade 
limestone  or  commercial  calcium  carbonate  preparations  would  seem 
to  be  the  most  efficient,  judging  from  the  Ohio  results,  while  finely 
ground  rock  phosphate  has  not  been  found  particularly  effective ;  its 
cheapness  and  more  general  availability  on  the  farm,  however,  must 
also  be  considered.  Good  results  have  been  reported  from  the  use  of 
a  mixture  of  acid  phosphate,  wood  ashes,  and  salt  in  the  proportion  of 
10  to  10  to  1  by  the  Purdue  Agricultural  Experiment  Station.  The 
effectiveness  of  slaked  lime  has  not  been  specifically  investigated. 

The  need  of  common  salt  by  all  farm  stock,  but  particularly  by 
animals  consuming  large  amounts  of  roughage,  is  well  recognized.  In 
the  compounding  of  mineral  mixtures  for  swine,  salt  is  also  valuable 
as  an  appetizer,  and  is  often  included,  therefore,  in  amounts  far  larger 
than  necessary. 

While  iodids  in  small  amounts  are  of  proven  value  in  certain 
specific  instances,  as  already  explained,  their  general  use  in  mineral 
mixtures  is  unnecessary  and  therefore  not  warranted. 

The  inclusion  of  purgatives,  drugs,  and  inert  fillers  in  mineral 
mixtures  is  to  be  condemned.  It  is  because  of  the  general  use  of  such 
substances,  rather  than  substances  of  nutritive  value,  that  commercial 
mineral  mixtures  should  be  regarded  with  suspicion.  Glauber's  salts, 
Epsom  salts,  potassium  chlorid,  lye,  and  copperas,  have  no  place  in 
the  rations  of  healthy  farm  animals.  As  Forbes  so  aptly  says  when 


J$  BULLETIN  No.  250  [May, 

speaking  of  mineral  mixtures  for  swine,  "healthy  pigs  do  not  need 
these  drugs,  and  sick  pigs  need  medicines  chosen  with  reference  to 
the  particular  disorders  from  which  they  suffer."  The  use  of  inert 
substances,  such  as  slack  coal,  charcoal,  and  sulfur,  cannot  be  said  to 
add  anything  to  the  value  of  mineral  mixtures,  tho  possibly  they  may 
improve  intestinal  conditions  in  some  unknown  way. 

The  long  list  of  substances  that  are  often  mentioned  as  possible 
constituents  of  mineral  mixtures,  appears  to  have  confused  the  popular 
mind  on  this  subject.  There  is  nothing  mysterious  or  particularly 
complicated  about  the  compounding  of  a  satisfactory  mineral  mixture. 
A  mixture  consisting  of  common  salt  (or  tankage)  10  parts,  finely 
ground  limestone  45  parts,  and  steamed  bone  meal  45  parts,  has  as 
much  to  commend  it  as  any  other  for  swine  feeding.  This  mixture 
contains  only  calcium  supplements  of  proven  value,  with  a  small 
amount  of  salt  or  tankage  to  increase  its  palatability  and  to  contribute 
sodium  and  chlorin,  in  which  grains  are  deficient.  It  is  therefore 
unnecessary  and  wasteful  to  purchase  and  use  complex  commercial 
mixtures. 

Mineral  supplements  should  be  used  in  swine  feeding  when  skim 
milk,  tankage,  or  legume  pasture  is  not  available.  The  supplements 
may  be  mixed  with  the  ground  concentrates  in  the  proportion  of  2  to 
100,  or  may  be  self -fed. 

THE  ECONOMIC  VALUE  OF  MINERAL  FEEDING 

While  the  value  of  a  greater  concentration  of  calcium  in  the  ration 
of  swine  than  that  afforded  by  cereal  or  all-seed  rations  seems  well 
established  in  so  far  as  bone  growth  and  development  are  concerned, 
its  value  is  not  so  clear  from  the  purely  economic  standpoint  in  the 
raising  of  pigs  for  market.  The  addition  of  calcium  supplements  to 
cereal  or  all-seed  rations  has  not  in  all  cases  produced  more  rapid  or 
more  economical  gains,  the  experience  of  the  Ohio  and  Wisconsin  Sta- 
tions being  in  this  particular  in  close  agreement.  In  the  experiments 
performed  at  the  Iowa  Experiment  Station,  and  reported  in  farm 
journals  and  elsewhere,  somewhat  more  rapid  and  economical  gains 
resulted  from  the  use  of  mineral  supplements  with  rations  of  cereals, 
seed  by-products,  and  blood  meal,  but  when  such  rations  were  supple 
mented  with  adequate  amounts  of  tankage  or  good  legume  pasture,  no 
obvious  beneficial  results  were  in  general  obtained  thru  the  use  of 
mineral  mixtures. 

However,  the  practice  of  feeding  mineral  supplements  to  growing 
and  fattening  swine  has  become  so  common  among  farmers  and  stock 
feeders,  and  the  claims  frequently  made  for  mineral  mixtures  have 
become  so  extreme  that  the  situation  calls  for  investigation.  The  fol- 
lowing series  of  experiments  was  therefore  undertaken,  primarily  to 


1924}  MINERAL  SUPPLEMENTS  IN  SWINE  FEEDING  97 

determine  whether  good  swine  rations  are  in  need  of  mineral  supple- 
ments. The  selection  of  the  minerals  used  in  these  experiments  was 
based  more  upon  their  common  availability  on  Illinois  farms  than  upon 
any  proven  superiority  over  other  minerals.  In  fact,  in  the  latter  re- 
spect the  selection  was  not  particularly  fortunate,  as  judged  by  the 
latest  findings  of  the  Ohio  Experiment  Station.  Most  of  the  work  was 
concerned  simply  with  the  rate  and  economy  of  gains  of  the  several 
groups  of  pigs,  tho  the  last  year 's  work  involved  also  the  measurement 
and  analysis  of  bones. 


FEEDING  EXPERIMENTS 

The  240  pigs  used  in  these  experiments  were  raised  on  the  Univer- 
sity Farm,  and  consisted  of  Poland  Chinas,  Duroc-Jerseys,  Chester 
Whites,  and  Hampshires,  with  some  Berkshires,  Large  Yorkshires,  and 
cross-breds.  All  lots  contained  20  pigs  at  the  start  of  the  experiment. 
Lots  to  which  minerals  were  offered  were  treated  uniformly  with  other 
lots  receiving  the  same  ration  without  added  minerals.  Data  bearing 
on  the  economy  of  gains  were  taken  in  each  test,  and  in  some  cases  the 
bones  were  analyzed  after  slaughter. 

The1  experiments,  for  the  most  part,  covered  the  period  from 
shortly  after  weaning  time  until  an  average  marketable"  weight  of  225 
pounds  had  been  attained  in  each  lot.  The  pigs  were  weighed  indi- 
vidually every  two  weeks  during  the  experiments,  the  weighing  being 
done  before  the  morning  feed  was  given.  The  pens  used  for  dry-lot 
feeding  were  free  from  vegetation.  They  were  provided  with  small 
movable  houses  and  sunshades  in  winter  and  summer. 

The  feeds  used  were  No.  2  to  No.  4  yellow  shelled  corn,  60  percent 
tankage,  old  process  linseed  oil  meal,  and  grey  flour  middlings. 

The  mineral  supplements  used  were  slack  coal,  charcoal,  air-slaked 
lime,  ground  limestone,  rock  phosphate,  and  salt.  The  coal  was  a  cheap 
grade  of  slack  coal.  The  charcoal  was  a  good  grade  of  commercial 
charcoal.  The  air-slaked  lime  was  commercial  slaked  lime  produced 
from  quicklime.  The  limestone  and  rock  phosphate  were  secured  from 
the  fertilizer  bins  of  the  Agronomy  Department  of  the  University. 
The  limestone  was  above  90  percent  purity  and  contained  about  36  per- 
cent calcium.  The  rock  phosphate  contained  13  percent  phosphorus 
as  a  minimum,  which  would  mean  that  the  calcium  content  was  about 
31  percent.  The  salt  was  ordinary  barrel  salt. 

The  feed  costs  in  this  bulletin  are  expressed  in  terms  of  pounds  of 
feed  and  mineral  supplements  required  for  100  pounds  of  gain.  From 
these  data,  the  cost  of  gains  can  be  calculated  at  the  prevailing  prices. 
No  attempt  was  made  to  determine  the  amount  of  forage  consumed. 


98  BULLETIN  No.  250  [May, 

EXPERIMENT   I:     MINERAL   SUPPLEMENTS   USED   WITH 

CORN,  MIDDLINGS,  AND  TANKAGE,  WITH  AND 

WITHOUT  RAPE  PASTURE 

The  first  year's  work  was  concerned  with  the  advisability  of  pro- 
viding mineral  supplements  for  pigs  on  a  ration  of  corn,  middlings, 
and  tankage,  with  and  without  access  to  rape  pasture.  One  hundred 
and  twenty  pigs,  averaging  43  pounds  in  weight,  were  divided  into 
six  lots  and  were  started  on  experiment  June  21,  1919.  Three  of  the 
six  lots  were  fed  in  dry  lot  and  three  were  allowed  rape  pasture  in  ad- 
dition to  their  concentrate  ration.  The  pigs  in  Lots  1,  2,  and  3  were 
hand-fed  a  full  ration  of  corn  and  were  allowed  about  0.4  pound  of 
tankage  and  0.8  pound  of  middlings  daily  per  head  after  the  first 
four  weeks.  For  Lots  4,  5,  and  6  (the  pasture  lots),  the  allowance  of 
tankage  and  middlings  was  cut  down  from  these  figures.  During  the 
period  of  pasture  feeding  (from  June  19  to  October  11),  the  daily 
allowance  of  tankage  was  from  0.25  to  0.30  pound,  and  of  middlings 
from  0.5  to  0.75  pound  per  head  after  the  first  few  weeks.  After 
October  11  these  three  lots  were  given  0.3  pound  of  tankage  and  0.75 
pound  of  middlings  per  head  daily.  The  pigs  in  Lots  1  and  4  received 
no  mineral  supplements.  Lots  2  and  5  were  offered  four  supplements 
in  separate  compartments  of  a  self-feeder,  i.e.,  coal,  limestone,  rock 
phosphate,  and  salt ;  while  Lots  3  and  6  were  given  their  choice  of  six 
supplements,  including  the  above  four  with  the  addition  of  charcoal 
and  air-slaked  lime.  All  lots  were  continued  to  an  average  weight  of 
approximately  225  pounds. 

RESULTS  OF  EXPERIMENT  I 

Little  difference  was  found  in  the  feed  consumption  or  in  the  rate 
and  economy  of  gains  among  the  groups  fed  in  dry  lot.  While  the  pigs 
receiving  no  minerals  made  the  slowest  and  most  expensive  gains  on 
the  average,  the  differences  as  compared  with  the  other  lots  were 
probably  too  small  to  be  significant. 

Among  the  lots  on  forage  there  were  also  no  considerable  differ- 
ences as  regards  feed  consumption  or  rate  or  economy  of  gains.  On 
an  average,  the  no-mineral  pigs  made  the  slowest  but  also  the  most 
economical  gains. 

In  all  lots  more  of  the  coal  was  consumed  than  of  all  other  mineral 
supplements  put  together.  The  consumption  of  coal  by  Lot  5  was  par- 
ticularly great,  twice  as  much  being  consumed  as  by  any  other  lot. 
Contrasted  with  this  large  consumption  of  coal,  comparatively  little 
of  the  calcium  supplements  (limestone  and  rock  phosphate)  was  eaten. 
A  close  correlation  between  the  consumption  of  coal  and  of  calcium 
supplements  is  to  be  noted  such  that  the  greater  the  consumption  of 


MINERAL  SUPPLEMENTS  IN  SWINE  FEEDING 


99 


TABLE  3. — EESULTS  OF  EXPERIMENT  I 

Mineral  Supplements  Fed  to  Pigs  on  a  Eation  of  Corn,  Middlings,  and  Tankage, 
With  and  Without  Access  to  Eape  Pasture 


Lot  No                 

1 

2 

3 

4 

5 

6 

Ration                

Corn,  tankage,  and  middlings 

Forage                    

None 

Rape 

Mineral  supplements  (free 
choice) 

None 

Self- 
fed 

Self- 
fed 

None 

Self- 
fed 

Self- 
fed 

No  of  pigs  at  beginning       .... 

20 
18 
196 

(Ibs.) 
43 
130 
225 
.89 

3.28 
.37 
.78 
4.43 

370 
41 

87 
498 

20 
18 
189 

(Ibs.) 
43 
134 
226 
.95 

3.31 
.37 

.78 
4.46 

349 
39 

82 
470 

(oz.) 

1.18 
.12 
.09 
.15 

1.54 
(Ibs.) 
10.2 

20    * 
19 
196 

(Ibs.) 
43 
134 
225 
.91 

3.30 
.37 
.78 
4.45 

362 
40 

85 

487 

(oz.) 
.89 
.18 
.13 
.19 
.26 
.01 
1.66 
(Ibs.) 
11.3 

20 
15 
175 

(Ibs.) 
43 
150 
227 
.98 

3.44 
.27 
.67 
4.38 

353 

27 
69 
449 

20 
19 

182 

(Hw.) 
42 
144 
225 
1.00 

3.57 
.27 

.68 
4.62 

356 
27 
67 
450 

(oz.) 
2.52 
.05 
.07 
.18 

2.82 
(Ibs.) 
17.5 

20 
20 
189 

(Ibs.) 
42 
142 
230 
1.01 

3.64 
.27 
.68 
4.59 

361 

27 
68 
456 

(oz.) 
.99 
.14 
.10 
.15 
.31 
.03 
1.72 

(Ibs.) 
10.7 

No  of  pigs  at  end  

Days  on  experiment  

Average  weight  per  pig 
Initial  weight  

Weight  on  Oct.  11  

Final  weight   

Daily  gain                       

Average  daily  ration 
Corn      

Tankage  

Middlings  

Total  

Concentrates  per  100  pounds  gain 
Corn  

Tankage  

Middlings  

Total  

Mineral    supplements    consumec 
daily  per  pig 
Coal  

Limestone  

Rock  phosphate  

Salt  

Charcoal  

Air-slaked  lime  

Total  

Mineral    supplements    consumec 
per  100  pounds  gain  

NOTE. — During  the  course  of  the  experiment  several  pigs  died  or  were  re- 
moved for  various  reasons.  In  some  cases  substitutions  were  made.  In  brief,  two 
pigs  were  withdrawn  from  Lot  1  on  October  11  and  25,  respectively,  for  lack  of 
thrift.  One  of  these  pigs  weighed  46  pounds  when  the  average  lot  weight  was  130 
pounds;  the  other  weighed  117  pounds  when  the  average  lot  weight  was  144 
pounds.  In  Lot  2,  one  pig  died  on  December  6  and  one  was  withdrawn  on  Decem- 
ber 19  on  account  of  inversion  of  the  uterus.  In  Lot  3,  one  pig  died  as  the  result 
of  vaccination  on  July  6  and  was  replaced  by  another  pig;  while  on  October  11  a 
second  pig  was  withdrawn  because  of  being  badly  ruptured.  In  Lot  4,  five  pigs 
died  between  October  8  and  November  13,  the  cause  of  death  being  diagnosed  as 
hemorrhagic  septicemia.  In  Lot  5,  one  pig  died  on  July  11  as  a  result  of  vaccina- 
tion and  was  replaced  by  another  pig  of  approximately  the  same  weight;  while 
on  November  25  a  second  pig  died  from  what  appeared  to  be  hemorrhagic  sep- 
ticemia. In  Lot  6,  one  pig  died  on  August  3,  cause  unknown,  and  was  replaced  by 
another  pig;  while  on  August  2  one  pig  was  killed  and  was  found  to  have 
cirrhosis  of  the  cord.  This  pig  was  replaced  by  another  of  the  same  weight. 


100  BULLETIN  No.  250  [May, 

coal,  the  less  the  consumption  of  limestone  and  rock  phosphate.  The 
intake  of  salt  was  fairly  uniform,  averaging  1  part  to  430  parts  of 
concentrates,  while  that  of  air-slaked  lime  was  insignificant. 

The  daily  concentrate  ration,  according  to  the  average  analyses  of 
Forbes,  contained  about  5.5  grams  of  calcium  for  Lots  1,  2,  and  3,  and 
about  4.0  grams  for  the  lots  on  forage.  Since  forage  would  furnish 
considerable  calcium,  all  lots  probably  received  sufficient  amounts  of 
this  element  entirely  aside  from  its  intake  in  the  form  of  a  supplement. 
The  minerals  fed  Lots  2,  3,  and  6  probably  furnished  2  to  2.5  grams 
of  calcium  per  head  per  day  and  those  fed  Lot  5  about  1  gram. 

EXPERIMENT  II:     PROVIDING  A  MINERAL  MIXTURE  IN 
THE  SELF-FEEDER  TO  PIGS  ON  PASTURE 

The  experiment  of  1919  showed  that  pigs  will  consume  only  small 
amounts  of  calcium  supplements  when  allowed  free  access  to  them  in 
separate  compartments  of  a  self-feeder  and  when,  also,  they  are 
allowed  free  access  to  coal.  Apparently  the  consumption  of  large 
amounts  of  coal  diminished  their  appetite  for  the  more  valuable  cal- 
cium supplements.  Since  it  seems  advisable  to  feed  mineral  supple- 
ments to  pigs  in  a  self-feeder,  further  work  was  undertaken  in  1920 
to  determine  the  value  of  a  mineral  mixture  when  offered  to  pigs  in 
this  manner. 

On  July  10,  1920,  four  lots  of  20  pigs  each  were  started  on  experi- 
ment, receiving  the  following  concentrate  rations  and  having  free 
access  to  blue-grass  pasture : 

Lot  1.     Two-thirds  ration  of  corn.     No  mineral  supplements. 

Lot  2.     Two-thirds  ration  of  corn.    Free  access  to  mineral  mixture. 

Lot  3.  Full  ration  of  corn  and  0.25  pound  of  tankage  per  head  daily.  No 
mineral  supplements. 

Lot  4.  Full  ration  of  corn  and  0.25  pound  of  tankage  per  head  daily.  Free 
access  to  mineral  mixture. 

On  October  2  all  lots  were  removed  from  pasture  and  put  on  a  full 
feed  of  corn  and  0.4  pound  of  tankage  daily  per  head.  The  mineral 
mixture  used,  consisting  of  coal  5  parts,  and  air-slaked  lime,  rock  phos- 
phate, and  salt  each  1  part,  was  offered  to  Lots  2  and  4  thruout  the  ex- 
periment, during  both  pasture  and  dry-lot  feeding.  All  lots  were  car- 
ried to  an  average  weight  of  approximately  225  pounds. 

RESULTS  OF  EXPERIMENT  II 

Little  difference  is  to  be  noted  in  the  feed  consumption  or  the  rate 
or  economy  of  gains  between  comparable  lots  in  this  experiment. 
While  the  most  economical  gains  were  made  by  the  two  lots  receiving 


MINERAL  SUPPLEMENTS  IN  SWINE  FEEDING 


101 


TABLE  4. — RESULTS  OF  EXPERIMENT  II 
Mineral  Mixture  Provided  in  a  Self -Feeder  to  Pigs  on  Pasture 


Lot  No  

1 

2 

3       1           4 

Ration  on  pasture1  

Two-thirds  ration 
corn 

Full  ration  of  corn  and 
0.25  pound  of  tankage 
per  head  daily 

Ration  in  dry  lot  

Full  ration  of  corn  and  0.4  pound  of  tankage 
per  head  daily 

Mineral  mixture  

None 

Self-fed 

None 

Self-fed 

No.  of  pigs  at  beginning.  .  .  . 
No.  of  pigs  at  end  

20 
19 
203 

(Ibs.) 
46 
107 
226 
.89 

3.96 
.32 
4.28 

448 
36 
484 

20 
19 
196 

(J&B.) 

16 
109 
224 
.90 

3.94 
.31 
4.25 

440 
35 
475 
(oz.) 
2.04 

14.2 

20 
19 
227 
(Jfo.) 

46 

75 
227 

.77 

3.54 
.24 
3.78 

461 
32 
493 

20 
16 

224 
(Ibs:) 
46 
79 
229 
.75 

3.39 
.23 
3.62 

450 
31 
481 
(02.) 
2.19 

18.1 

Days  on  experiment  

Average  weight  per  pig 
Initial  weight  

Weight  on  October  2  .... 
Final  weight  

Daily  gain  

Average  daily  ration 
Corn  

Tankage  

Total  

Concentrates  consumed  per  100 
pounds  gain 
Corn  

Tankage  

Total  

Mineral     supplements     con- 
sumed daily  per  pig  .  .  . 

Mineral     supplements      con- 
sumed per  100  pounds  gain 

NOTE. — In  this  experiment  also  certain  changes  were  made  in  each  group  of 
pigs  owing  to  death  or  withdrawal  and  to  substitutions. 

In  Lot  1,  one  pig  was  withdrawn  on  July  29  because  of  scouring  and  ema- 
ciation and  was  replaced  by  another  pig  of  approximately  the  same  weight;  on 
October  14  one  pig  was  removed  with  hemorrhagic  septicemia.  In  Lot  2,  two  pigs 
were  withdrawn  on  July  24  and  29,  respectively,  and  replaced  by  other  pigs; 
while  on  October  2  four  pigs  wert  withdrawn  with  hemorrhagic  septicemia,  three 
of  them  being  put  back  on  experiment  two  weeks  later.  In  Lot  3,  one  pig  was  re- 
moved on  July  29  and  another  on  August  7,  substitutions  being  made;  while  on 
July  31  four  pigs  died  of  the  heat  and  were  replaced  by  four  others  of  nearly  the 
same  weight ;  on  October  2  one  pig  was  removed  from  experiment  because  of  fail- 
ure to  grow,  weighing  only  27  Ibs.  when  the  average  weight  of  the  lot  was  75  Ibs. 
A  substitution  was  made  for  one  pig  removed  from  Lot  4  on  August  14  because 
of  hemorrhagic  septicemia,  and  removal  of  three  pigs  for  the  same  cause  was  made 
on  September  18,  October  2,  and  January  20,  with  no  replacements;  on  January 
22  another  pig  was  withdrawn  because  of  lack  of  thrift.  This  latter  pig  weighed 
65  Ibs.,  while  the  average  lot  weight  was  188  Ibs. 

1  All  lots  were  on  blue-grass  pasture  until  October  2. 

minerals,  the  differences  are  not  great  enough  to  justify  the  conclusion 
that  free  access  to  mineral  supplements  definitely  improved  the  rations 
used  in  this  test.  As  a  matter  of  fact,  under  the  prices  prevailing  dur- 
ing the  experiment,  the  cost  of  mineral  supplements  and  concentrates 


102 


BULLETIN  No.  250 


[May, 


per  100  pounds  of  gain  in  Lot  2  were  practically  the  same  as  the  cost 
of  concentrates  per  100  pounds  gain  in  Lot  1 ;  while  for  Lot  4  as 
compared  with  Lot  3  the  cost  of  gains  was  greater  when  mineral  sup- 
plements were  fed. 

In  Lots  2  and  4  the  consumption  of  mineral  supplements,  and  par- 
ticularly calcium  supplements,  was  greater  than  in  the  experiment  of 
the  preceding  year  when  all  supplements  were  offered  in  separate  com- 
partments of  the  self-feeder.  However,  in  spite  of  this  increased  in- 
take of  calcium,  no  marked  improvement  in  the  ration  was  shown,  in- 
dicating that  the  concentrate  ration  used  needed  no  further  supple- 
menting than  that  afforded  by  access  to  pasture  while  this  was 
available. 

EXPERIMENT  III :  MINERAL  MIXTURE  U§ED  WITH  CORN, 

LINSEED  OIL  MEAL,  AND  MIDDLINGS,  WITH 

ACCESS  TO  BLUE-GRASS  PASTURE 

The  purpose  of  the  third  experiment  was  to  determine  the  ad- 
vantages, if  any,  of  adding  mineral  supplements  to  a  ration  of  corn, 
linseed  oil  meal,  and  middlings,  when  the  pigs  had  access  also  to  blue- 
grass  pasture.  The  mineral  mixture  used  contained  coal  5  parts,  and 
ground  limestone,  rock  phosphate,  and  salt  each  1  part.  By  actual 
analysis,  this  mixture  was  found  to  contain  12.38  percent  of  calcium. 
The  feeds  used  in  this  experiment  were  also  analyzed,  with  the  re- 
sults given  in  Table  5. 

TABLE  5. — ANALYSIS  OF  FEEDS  USED  IN  EXPFRIMENT  III 
(Percent  of  Fresh  Substance) 


Dry 

matter 

N-free 

extract 

Crude 
protein 

Ether 
extract 

Ash 

Crude 
fiber 

Wheat  middlings  .... 
Corn  

90.93 
89.33 

60.73 
76.98 

17.79 
8.57 

1.53 
0.72 

4.91 
1.24 

5.97 
1.82 

Oil  meal  .  . 

90.52 

45.84 

29.21 

1.46 

6.07 

7.94 

ECONOMY  OP  GAINS  IN  EXPERIMENT  III 

The  average  daily  feed  consumption  per  pig  was  practically  the 
same  in  both  lots,  tho  the  rate  and  economy  of  gains  were  more  favor- 
able in  the  group  having  access  to  minerals.  The  pigs  offered  the 
mineral  mixture  gained  an  average  of  0.07  pound  more  per  day  than 
the  pigs  receiving  no  minerals,  at  a  saving  of  37  pounds  of  feed  per 
100  pounds  of  gain.  Statistical  analysis  of  the  individual  daily  gains 
indicates,  however,  that  the  average  lot  difference  in  rate  of  gain  is 
of  no  significance.  The  cost  of  gains  was  somewhat  less  in  the  lot  fed 
mineral  supplements  than  in  the  lot  not  so  fed,  when  the  feeds  and 
supplements  were  charged  at  the  prices  prevailing  during  the  experi- 


1924} 


MINERAL  SUPPLEMENTS  IN  SWINE  FEEDING 


103 


ment.  The  consumption  of  mineral  supplements  by  Lot  2  was  low  as 
compared  with  that  in  the  preceding  experiments,  about  one  pound 
being  consumed  per  pig  every  20  days.  A  striking  difference  between 
the  two  lots  of  pigs  was  noted  in  the  amount  of  rooting  in  the  pasture. 
The  pigs  receiving  no  mineral  supplements,  rooted  up  their  pasture 
completely,  while  the  lot  receiving  minerals  did  no  considerable  rooting. 

SIZE  AND  COMPOSITION  OF  THE  BONES  OF  THE  PIGS 

IN  EXPERIMENT  III 
t 
At  the  conclusion  of  this  feeding  test,  five  pigs  from  each  lot  were 

slaughtered  at  a  local  slaughter  house  and  the  leg  bones  removed  for 
measurement  and  analysis.  At  the  same  time,  six  sows  from  Lot  1, 
and  five  from  Lot  2,  were  bred  and  continued  on  their  respective 
rations  until  litters  were  farrowed  and  weaned. 


TABLE  6. — EESULTS  OF  EXPERIMENT  III 

Mineral  Mixture  Fed  to  Pigs  on  a  Ration  of  Corn,  Linseed  Oil  Meal,  and 
Middlings,  With  Access  to  Blue-Grass  Pasture 


Lot  No  

1 

2 

Ration  

Full  ration  of  corn,  linseed  oil- 
meal,  and  middlings      Access  to 
blue-grass  pasture. 

Mineral  mixture  

None 

Self-fed 

No.  of  pigs  at  beginning  

20 
19 
144 
(Ibs.) 
65 
206 
.93 

3.39 
.51 

.79 

505             * 
365 
55 
85 

20 
19 
144 
(Ibs.) 
64 
211 
1.00 

3.40 
.51 
.79 

468 
338 
51 
79 

(Of.) 

.83 

(Ibs.} 
5.14 

No.  of  pigs  at  end  

Days  on  experiment  

Average  weight  per  pig 
Initial  weight  

Final  weight  

Daily  gain  

Average  daily  ration  per  pig 
Corn  

Linseed  oil  meal  

Middlings  

Concentrates  consumed  per  100  pounds 
gain  

Corn  .... 

Linseed  oil  meal  .    . 

Middlings      . 

Average  daily  consumption  of  mineral 
mixture  per  pig  

Mineral    mixture    consumed    per    100 
pounds  gain  

NOTE. — On  July  30  three  pigs  were  removed  from  Lot  1  for  lack  of  thrift  and 
were  replaced  by  three  other  pigs  weighing  considerably  more;  on  November  12 
one  pig  was  removed  from  this  group  because  of  sickness,  no  replacement  being 
made.  In  Lot  2,  two  pigs  were  removed  on  August  6  and  September  25,  respec- 
tively, because  of  injury,  a  substitution  being  made  for  the  first  pig  removed  but 
not  for  the  second. 


104 


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MINERAL  SUPPLEMENTS  IN  SWINE  FEEDING 


The  results  of  the  measurement  of  bones  from  the  pigs  killed  at 
the  termination  of  the  experiment  are  given  in  Table  7,  and  the 
results  of  their  analysis  for  moisture,  protein,  and  ash,  in  Table  8. 

A  study  of  Table  7  does  not  reveal  any  distinctive  differences  as 
regards  the  size  of  bone  between  the  two  lots  of  pigs.  However,  the 
pigs  of  Lot  2  tended  distinctly  to  develop  bones  of  greater  specific 
gravity  than  the  pigs  of  Lot  1,  particularly  with  respect  to  the 
humerus  and  the  femur.  From  the  analytical  results  summarized  in 
Table  8,  no  marked  differences  in  the  composition  of  the  bones  appeared 
to  exist  between  the  two  groups  of  pigs.  The  bones  of  pigs  having 
access  to  mineral  supplements  had  a  much  higher  average  ash  con- 
tent (dry  basis)  than  those  of  the  pigs  not  having  access  to  mineral 
supplements,  but  individual  differences  among  the  pigs  within  the 
two  lots  were  so  great  that  no  definite  significance  can  be  attached  to 
the  average  difference.  However,  as  the  last  column  shows,  there 
seems  to  be  a  distinct  difference  as  regards,  the  weight  of  ash  per 
cubic  centimeter  of  volume,  the  average  figure  for  the  five  pigs  of 
Lot  1  being  0.317  gram,  and  for  Lot  2,  0.351  gram.  Only  one  case 
of  overlapping  occurs  between  the  individual  figures  of  the  two  groups, 
the  highest  value  for  Lot  1  being  0.329  gram,  and  the  lowest  for 
Lot  2,  0.328  gram,  so  that  the  difference  evidently  possesses  consider- 
able significance.  The  mineral  mixture  offered  to  the  pigs  in  Lot  2 
apparently  had  a  distinctly  favorable  effect  in  developing  denser  and 
probably  stronger  bone  than  would  have  been  produced  otherwise. 

TABLE  8. — CHEMICAL  ANALYSIS  OF  BONES  FROM  FIVE  PIGS  IN  EACH  OF 
THE  LOTS  OF  EXPERIMENT  III 


No.  of 
pig 

Wt.  of 
pig 

Wt.  of 
fresh 
bones 

Total 
moisture 
in  fresh 
bones 

Crude 
protein 

Crude 
ash 

Ash 
per  cc. 
of  vol. 

Calculated  on  dry  basis 

Lot  1 — Receiving  No  Mineral  Supplements 


Ibs. 

gms. 

perct. 

perct. 

perct. 

ffm. 

93PC 

223 

756 

37.64 

26.22 

39.5S 

.324 

9DJ 

194 

785 

36.70 

23.14 

39.97 

.329 

40DJ 

177 

672 

31.94 

24.70 

36.18 

.311 

43DJ 

195 

689 

33.28 

25.83 

36.23 

.300 

30DJ 

224 

570 

35.27 

26.67 

38.92 

.320 

Average 

202.6 

694.4 

34.93 

25.91 

38.18 

.317 

Lot  2 — Having  Access  to  a  Mineral  Mixture 


33DJ 

240 

752 

31.73 

27.20 

44.59 

.404 

ODJ 

191 

610 

37.25 

26.36 

43.00 

.356 

13DJ 

190 

673 

38.44 

27.39 

41.09 

.332 

30DJ 

196 

653 

31.21 

24.80 

37.72 

.333 

3PC 

247 

837 

34.58 

27.53 

38.95 

.328 

Average 

212.8 

705 

34.64 

26.66 

41.07 

.351 

106  BULLETIN  No.  250  [May, 

MINERAL  MIXTURE  FOR  PREGNANT  AND 

LACTATING  SOWS 
FEED  AND  REPRODUCTION  RECORDS 

The  feed  and  reproduction  records  of  the  sows  selected  from  the 
two  lots  of  Experiment  III  are  given  in  Tables  9  and  10.  While  the 
average  daily  feed  consumption  of  the  two  groups  was  approximately 
the  same,  .the  sows  offered  the  mineral  mixture  gained  faster  at  a 
much  lower  feed  cost  than  the  sows  without  added  minerals.  In 
this  connection  it  should  be  borne  in  mind  that  the  pasture  available 
during  this  test  was  winter  pasture  and  very  probably  did  not  supple- 
ment to  any  considerable  extent  the  calcium-poor  concentrate  rations. 
The  sows  of  Lot  2  produced  larger  and  heavier  litters  than  the  sows  of 
Lot  1,  on  the  average,  tho  the  average  weight  per  pig  was  larger  for  the 
litters  of  Lot  1.  During  the  suckling  period,  the  pigs  in  both  groups 
did  very  poorly,  owing  to  a  chronic  enteritis.  The  pigs  weaned  from 
the  sows  of  Lot  1  were,  on  the  average,  heavier  than  those  weaned  from 
the  sows  of  Lot  2.  The  individual  data  concerning  the  weaning  weights 
of  the  pigs  are  given  in  Table  11. 

SIZE  AND  COMPOSITION  OF  BONES 

After  their  pigs  were  weaned,  the  sows  were  slaughtered  and  their 
leg  bones  taken  for  examination.  In  Table  12  are  given  the  measure- 
ments of  these  bones  and  in  Table  13  their  composition.  In  this  test 
the  bones  were  analyzed  for  calcium  by  the  McCrudden  method,  in 
addition  to  analyses  for  dry  matter,  protein,  and  ash. 

No  significant  differences  in  size  or  specific  gravity  of  the  bones 
are  evident  between  the  two  groups  of  sows.  The  sows  of  Lot  2,  being 
heavier  than  those  of  Lot  1,  possessed  heavier  bones  on  the  average, 
tho  variations  within  each  lot  were  so  great  that  no  true  lot  difference 
can  be  assumed.  Similarly  (Table  13)  the  composition  of  the  bones 
of  the  two  groups  of  sows  did  not  seem  to  be  affected  by  the  inclusion 
of  mineral  supplements  in  the  ration.  The  sows  having  access  to  the 
mineral  mixture  had  on  an  average  a  higher  percentage  of  ash  and 
calcium  in  their  bones  and  a  greater  weight  of  ash  per  cubic  centi- 
meter of  volume,  but  the  individual  differences  within  the  two  lots 
were  so  great  that  no  positive  conclusions  concerning  the  meaning  of 
these  average  differences  seem  justified.  In  other  words,  there  is  no 
positive  evidence,  from  a  physical  and  chemical  examination  of  the  leg 
bones  of  these  sows,  that  the  ration  of  corn,  linseed  oil  meal,  and 
middlings  with  access  to  winter  pasture  was  improved  at  all  from  a 
nutritional  standpoint  by  the  self-feeding  of  the  mineral  mixture 
used  in  this  experiment.  The  heavy  strain  of  reproduction  and  lacta- 
tion seems  to  have  been  as  well  borne  by  the  sows  receiving  no  mineral 
supplements  as  by  the  sows  having  access  to  a  mineral  mixture. 


1924]  MINERAL  SUPPLEMENTS  IN  SWINE  FEEDING  107 

TABLE  9. — FEED  AND  WEIGHT  RECORDS  FOR  PREGNANT  Sows:     EXPERIMENT  III 


I  ot  No  

1 

2 

Forage  (winter  pasture)  

Blue  grass 

Blue  grass 

Ration  

Corn 
Oil  meal 

Corn 
Oil  meal 

Middlings 

Middlings 
Mineral  mixture 

Number  of  sows  

6 

5 

Days  on  experiment  (average)  

149 

143 

Average  weight  per  sow  

(Ibs.) 

(Ibs.) 

Initial  weight  

215 

208 

Final  weight  

311 

340     • 

Daily  gain  

.64 

.  .87 

Average  daily  ration  per  sow  

Corn  

2.89 

2.87 

Oil  Meal  

.50 

.51 

Middlings  

1.94 

1.98 

Total  

5.33 

5.36 

Concentrates  per  100  pounds  gain  

Corn  

449 

331 

Oil  meal  

78 

59 

Middlings  

301 

228 

Total  

828 

618 

Average  daily  consumption  of  mineral  mix- 
ture per  sow  

(oz.) 
1.22 

TABLE  10. — WEIGHTS  OF  LITTERS  WHEN  FARROWED 
Lot  1 — No  Mineral  Supplements 


Sow  

19DJ 

90DJ 

40DJ 

59DJ 

ODJ 

3PC 

Number  of  pigs  
Aver,  weight  (Ibs.)  .  .  . 

10 

1.84 

7 
2.19 

8 
2.32 

3 

2.27 

10 
1.92 

9 
2.41 

Lot  2 — Access  to  Mineral  Mixture 


Sow  

99DJ 

90DJ 

40DJ 

1DJ 

ODJ 

Number  of  pigs  
Aver,  weight  (Ibs.)  .  .  . 

11 

2.38 

10 
1.96 

10 
1.93 

10 
1.55 

6 
1.37 

TABLE  11. — WEIGHTS  OF  LITTERS  WHEN  WEANED 
Lot  1 — No  Mineral  Supplements 


Sow  

19DJ 

90DJ 

40DJ 

59DJ 

ODJ 

3PC 

Number  of  pigs  
Aver,  weight  (Ibs.)  .  .  . 

3 
23.3 

4 
20.5 

8 
14.0 

2 
16.0 

5 
17.2 

5 
21.8 

Lot  2 — Access  to  Mineral  Mixture 


Sow  

99DJ 

90DJ 

40DJ 

1DJ 

ODJ 

Number  of  pigs  

5 

4 

6 

4 

4 

Aver,  weight  (Ibs.)  .  .  . 

15.2 

14.7 

16.0 

13.7 

17.5 

NOTE. — The  pigs  during  their  suckling  period  were  troubled  with  necrotic 
enteritis,  in  consequence  of  which  they  did  not  attain  normal  weaning  weights 
in  eight  weeks. 


108 


BULLETIN  No.  250 


[May, 


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MINERAL  SUPPLEMENTS  IN  SWINE  FEEDING 


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110  BULLETIN  No.  250 


CONCLUSIONS 

1.  The  feeding  of  the  mineral  supplements  used  in  these  experi- 
ments, ad  libitum,  to  growing  and  fattening  pigs  on  rations  containing 
feeds   high   or   fairly   high   in   calcium — namely,   tankage   or   good 
pasture — has  little  effect,  if  any,  on  the  rate  or  economy  of  the  gains 
secured.     Possibly  slightly  more  rapid  gains  from  slightly  less  feed 
may  be  obtained  from  their  use.    Similar  results  may  be  expected  from 
rations  containing  liberal  amounts  of  skim  milk.     With  rations  not 
containing  sufficient  amounts  of  calcium-rich  feeds,  more  distinctly 
beneficial  results  might  be  expected  from  the  feeding  of  mineral  sup- 
plements.    Also,  with  other  mineral  supplements,  particularly  bone 
preparations  and  commercial  calcium  carbonate  products,  it  seems 
possible  from  the  investigations  of  other  experiment  stations  that  a 
greater  beneficial  effect  might  have  resulted  than  with  the  supple- 
ments here  used.1 

2.  If  mineral  mixtures  are  self-fed,  the  free  offering  of  coal  also, 
may  be  expected  to  reduce  the  consumption  of  minerals,  judging  from 
the  results  of  the  first  experiment  reported  in  this  bulletin.     Since 
there  is  no  experimental  evidence  that  the  consumption  of  coal  in  any 
way  benefits  the  pig,  and  since  there  is  no  good  reason  to  expect  that 
it  should,  its  use  in  mineral  mixtures  cannot  be  recommended. 

3.  When  tankage  or  pasture  is  included  in  the  rations,  mineral 
supplements  must  be  purchased  at  the  lowest  possible  price  to  be 
profitably  used  in  the  production  of  pigs  for  market.    Therefore,  com- 
mercial mineral  mixtures  cannot,  in  general,  be  recommended  for  this 
purpose. 

4.  While  the  addition  of  mineral  supplements  to  a  ration  of  corn, 
linseed  oil  meal,  middlings,  and  blue-grass  pasture,  has  no  great  or 
certain  effect  on  the  rate  or  economy  of  the  gains  secured,  it  does  dis- 
tinctly produce  denser  and  probably  stronger  bone.     However,  the 
sows  raised  on  this  ration  without  mineral  supplements  did  not  seem 
to  have  been  particularly  handicapped  during  the  production  and 
raising  of  their  first  litters  nor  to  have  depleted  seriously  their  min- 
eral reserves,  as  compared  with  sows  on  the  same  ration  having  access 
to  a  mineral  mixture. 


NOTE. — While  this  material  was  in  press,  the  Wisconsin  Agricultural  Experi- 
ment Station  has  published  a  preliminary  report  (Bui.  362,  pp.  103  and  104)  of 
two  years'  experimental  work  on  the  value  of  mineral  supplements  added  to  a 
well-balanced  ration  of  corn,  oats,  wheat  middlings,  linseed  oil  meal,  and  tankage, 
with  access  to  pasture  or  legume  hay.  Neither  in  the  growth  of  young  pigs  nor  in 
the  size  and  vigor  of  the  litters  farrowed  by  sows  on  experimental  feeding,  did  the 
added  minerals  exert  any  noticeable  effect. 


—70 


UNIVERSITY  OF  ILLINOIS-URBANA 


